/*
 * jdcoefct.c
 *
 * Copyright (C) 1994-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains the coefficient buffer controller for decompression.
 * This controller is the top level of the JPEG decompressor proper.
 * The coefficient buffer lies between entropy decoding and inverse-DCT steps.
 *
 * In buffered-image mode, this controller is the interface between
 * input-oriented processing and output-oriented processing.
 * Also, the input side (only) is used when reading a file for transcoding.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"

/* Block smoothing is only applicable for progressive JPEG, so: */
#ifndef D_PROGRESSIVE_SUPPORTED
#undef BLOCK_SMOOTHING_SUPPORTED
#endif

/* Private buffer controller object */

typedef struct {
    struct jpeg_d_coef_controller pub;/* public fields */

    /* These variables keep track of the current location of the input side. */
    /* cinfo->input_iMCU_row is also used for this. */
    JDIMENSION MCU_ctr;     /* counts MCUs processed in current row */
    int        MCU_vert_offset; /* counts MCU rows within iMCU row */
    int        MCU_rows_per_iMCU_row; /* number of such rows needed */

    /* The output side's location is represented by cinfo->output_iMCU_row. */

    /* In single-pass modes, it's sufficient to buffer just one MCU.
     * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks,
     * and let the entropy decoder write into that workspace each time.
     * (On 80x86, the workspace is FAR even though it's not really very big;
     * this is to keep the module interfaces unchanged when a large coefficient
     * buffer is necessary.)
     * In multi-pass modes, this array points to the current MCU's blocks
     * within the virtual arrays; it is used only by the input side.
     */
    JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];

#ifdef D_MULTISCAN_FILES_SUPPORTED
    /* In multi-pass modes, we need a virtual block array for each component. */
    jvirt_barray_ptr whole_image[MAX_COMPONENTS];
#endif

#ifdef BLOCK_SMOOTHING_SUPPORTED
    /* When doing block smoothing, we latch coefficient Al values here */
    int * coef_bits_latch;
#define SAVED_COEFS  6      /* we save coef_bits[0..5] */
#endif
} my_coef_controller;

typedef my_coef_controller * my_coef_ptr;

/* Forward declarations */
METHODDEF int decompress_onepass
JPP( ( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) );
#ifdef D_MULTISCAN_FILES_SUPPORTED
METHODDEF int decompress_data
JPP( ( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) );
#endif
#ifdef BLOCK_SMOOTHING_SUPPORTED
LOCAL boolean smoothing_ok JPP( (j_decompress_ptr cinfo) );
METHODDEF int decompress_smooth_data
JPP( ( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) );
#endif


LOCAL void
start_iMCU_row( j_decompress_ptr cinfo ) {
/* Reset within-iMCU-row counters for a new row (input side) */
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

    /* In an interleaved scan, an MCU row is the same as an iMCU row.
     * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
     * But at the bottom of the image, process only what's left.
     */
    if ( cinfo->comps_in_scan > 1 ) {
        coef->MCU_rows_per_iMCU_row = 1;
    } else {
        if ( cinfo->input_iMCU_row < ( cinfo->total_iMCU_rows - 1 ) ) {
            coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
        } else {
            coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
        }
    }

    coef->MCU_ctr = 0;
    coef->MCU_vert_offset = 0;
}


/*
 * Initialize for an input processing pass.
 */

METHODDEF void
start_input_pass( j_decompress_ptr cinfo ) {
    cinfo->input_iMCU_row = 0;
    start_iMCU_row( cinfo );
}


/*
 * Initialize for an output processing pass.
 */

METHODDEF void
start_output_pass( j_decompress_ptr cinfo ) {
#ifdef BLOCK_SMOOTHING_SUPPORTED
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

    /* If multipass, check to see whether to use block smoothing on this pass */
    if ( coef->pub.coef_arrays != NULL ) {
        if ( ( cinfo->do_block_smoothing ) && ( smoothing_ok( cinfo ) ) ) {
            coef->pub.decompress_data = decompress_smooth_data;
        } else {
            coef->pub.decompress_data = decompress_data;
        }
    }
#endif
    cinfo->output_iMCU_row = 0;
}


/*
 * Decompress and return some data in the single-pass case.
 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
 * Input and output must run in lockstep since we have only a one-MCU buffer.
 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 *
 * NB: output_buf contains a plane for each component in image.
 * For single pass, this is the same as the components in the scan.
 */

METHODDEF int
decompress_onepass( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) {
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
    JDIMENSION MCU_col_num; /* index of current MCU within row */
    JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
    JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
    int blkn, ci, xindex, yindex, yoffset, useful_width;
    JSAMPARRAY output_ptr;
    JDIMENSION start_col, output_col;
    jpeg_component_info * compptr;
    inverse_DCT_method_ptr inverse_DCT;

    /* Loop to process as much as one whole iMCU row */
    for ( yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
          yoffset++ ) {
        for ( MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
              MCU_col_num++ ) {
            /* Try to fetch an MCU.  Entropy decoder expects buffer to be zeroed. */
            jzero_far( (void FAR *) coef->MCU_buffer[0],
                      (size_t) ( cinfo->blocks_in_MCU * SIZEOF( JBLOCK ) ) );
            if ( !( *cinfo->entropy->decode_mcu )( cinfo, coef->MCU_buffer ) ) {
                /* Suspension forced; update state counters and exit */
                coef->MCU_vert_offset = yoffset;
                coef->MCU_ctr = MCU_col_num;
                return JPEG_SUSPENDED;
            }
            /* Determine where data should go in output_buf and do the IDCT thing.
             * We skip dummy blocks at the right and bottom edges (but blkn gets
             * incremented past them!).  Note the inner loop relies on having
             * allocated the MCU_buffer[] blocks sequentially.
             */
            blkn = 0;   /* index of current DCT block within MCU */
            for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
                compptr = cinfo->cur_comp_info[ci];
                /* Don't bother to IDCT an uninteresting component. */
                if ( !compptr->component_needed ) {
                    blkn += compptr->MCU_blocks;
                    continue;
                }
                inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];
                useful_width = ( MCU_col_num < last_MCU_col ) ? compptr->MCU_width
                               : compptr->last_col_width;
                output_ptr = output_buf[ci] + yoffset * compptr->DCT_scaled_size;
                start_col = MCU_col_num * compptr->MCU_sample_width;
                for ( yindex = 0; yindex < compptr->MCU_height; yindex++ ) {
                    if ( ( cinfo->input_iMCU_row < last_iMCU_row ) ||
                        ( yoffset + yindex < compptr->last_row_height ) ) {
                        output_col = start_col;
                        for ( xindex = 0; xindex < useful_width; xindex++ ) {
                            ( *inverse_DCT )( cinfo, compptr,
                                              (JCOEFPTR) coef->MCU_buffer[blkn + xindex],
                                              output_ptr, output_col );
                            output_col += compptr->DCT_scaled_size;
                        }
                    }
                    blkn += compptr->MCU_width;
                    output_ptr += compptr->DCT_scaled_size;
                }
            }
        }
        /* Completed an MCU row, but perhaps not an iMCU row */
        coef->MCU_ctr = 0;
    }
    /* Completed the iMCU row, advance counters for next one */
    cinfo->output_iMCU_row++;
    if ( ++ ( cinfo->input_iMCU_row ) < cinfo->total_iMCU_rows ) {
        start_iMCU_row( cinfo );
        return JPEG_ROW_COMPLETED;
    }
    /* Completed the scan */
    ( *cinfo->inputctl->finish_input_pass )( cinfo );
    return JPEG_SCAN_COMPLETED;
}


/*
 * Dummy consume-input routine for single-pass operation.
 */

METHODDEF int
dummy_consume_data( j_decompress_ptr cinfo ) {
    return JPEG_SUSPENDED;  /* Always indicate nothing was done */
}


#ifdef D_MULTISCAN_FILES_SUPPORTED

/*
 * Consume input data and store it in the full-image coefficient buffer.
 * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
 * ie, v_samp_factor block rows for each component in the scan.
 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 */

METHODDEF int
consume_data( j_decompress_ptr cinfo ) {
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
    JDIMENSION MCU_col_num; /* index of current MCU within row */
    int blkn, ci, xindex, yindex, yoffset;
    JDIMENSION start_col;
    JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
    JBLOCKROW buffer_ptr;
    jpeg_component_info * compptr;

    /* Align the virtual buffers for the components used in this scan. */
    for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
        compptr = cinfo->cur_comp_info[ci];
        buffer[ci] = ( *cinfo->mem->access_virt_barray )
                     ( (j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
                      cinfo->input_iMCU_row * compptr->v_samp_factor,
                      (JDIMENSION) compptr->v_samp_factor, TRUE );
        /* Note: entropy decoder expects buffer to be zeroed,
         * but this is handled automatically by the memory manager
         * because we requested a pre-zeroed array.
         */
    }

    /* Loop to process one whole iMCU row */
    for ( yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
          yoffset++ ) {
        for ( MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
              MCU_col_num++ ) {
            /* Construct list of pointers to DCT blocks belonging to this MCU */
            blkn = 0;   /* index of current DCT block within MCU */
            for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
                compptr = cinfo->cur_comp_info[ci];
                start_col = MCU_col_num * compptr->MCU_width;
                for ( yindex = 0; yindex < compptr->MCU_height; yindex++ ) {
                    buffer_ptr = buffer[ci][yindex + yoffset] + start_col;
                    for ( xindex = 0; xindex < compptr->MCU_width; xindex++ ) {
                        coef->MCU_buffer[blkn++] = buffer_ptr++;
                    }
                }
            }
            /* Try to fetch the MCU. */
            if ( !( *cinfo->entropy->decode_mcu )( cinfo, coef->MCU_buffer ) ) {
                /* Suspension forced; update state counters and exit */
                coef->MCU_vert_offset = yoffset;
                coef->MCU_ctr = MCU_col_num;
                return JPEG_SUSPENDED;
            }
        }
        /* Completed an MCU row, but perhaps not an iMCU row */
        coef->MCU_ctr = 0;
    }
    /* Completed the iMCU row, advance counters for next one */
    if ( ++ ( cinfo->input_iMCU_row ) < cinfo->total_iMCU_rows ) {
        start_iMCU_row( cinfo );
        return JPEG_ROW_COMPLETED;
    }
    /* Completed the scan */
    ( *cinfo->inputctl->finish_input_pass )( cinfo );
    return JPEG_SCAN_COMPLETED;
}


/*
 * Decompress and return some data in the multi-pass case.
 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 *
 * NB: output_buf contains a plane for each component in image.
 */

METHODDEF int
decompress_data( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) {
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
    JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
    JDIMENSION block_num;
    int ci, block_row, block_rows;
    JBLOCKARRAY buffer;
    JBLOCKROW buffer_ptr;
    JSAMPARRAY output_ptr;
    JDIMENSION output_col;
    jpeg_component_info * compptr;
    inverse_DCT_method_ptr inverse_DCT;

    /* Force some input to be done if we are getting ahead of the input. */
    while ( cinfo->input_scan_number < cinfo->output_scan_number ||
           ( cinfo->input_scan_number == cinfo->output_scan_number &&
             cinfo->input_iMCU_row <= cinfo->output_iMCU_row ) ) {
        if ( ( *cinfo->inputctl->consume_input )( cinfo ) == JPEG_SUSPENDED ) {
            return JPEG_SUSPENDED;
        }
    }

    /* OK, output from the virtual arrays. */
    for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
          ci++, compptr++ ) {
        /* Don't bother to IDCT an uninteresting component. */
        if ( !compptr->component_needed ) {
            continue;
        }
        /* Align the virtual buffer for this component. */
        buffer = ( *cinfo->mem->access_virt_barray )
                 ( (j_common_ptr) cinfo, coef->whole_image[ci],
                  cinfo->output_iMCU_row * compptr->v_samp_factor,
                  (JDIMENSION) compptr->v_samp_factor, FALSE );
        /* Count non-dummy DCT block rows in this iMCU row. */
        if ( cinfo->output_iMCU_row < last_iMCU_row ) {
            block_rows = compptr->v_samp_factor;
        } else {
            /* NB: can't use last_row_height here; it is input-side-dependent! */
            block_rows = (int) ( compptr->height_in_blocks % compptr->v_samp_factor );
            if ( block_rows == 0 ) {
                block_rows = compptr->v_samp_factor;
            }
        }
        inverse_DCT = cinfo->idct->inverse_DCT[ci];
        output_ptr = output_buf[ci];
        /* Loop over all DCT blocks to be processed. */
        for ( block_row = 0; block_row < block_rows; block_row++ ) {
            buffer_ptr = buffer[block_row];
            output_col = 0;
            for ( block_num = 0; block_num < compptr->width_in_blocks; block_num++ ) {
                ( *inverse_DCT )( cinfo, compptr, (JCOEFPTR) buffer_ptr,
                                  output_ptr, output_col );
                buffer_ptr++;
                output_col += compptr->DCT_scaled_size;
            }
            output_ptr += compptr->DCT_scaled_size;
        }
    }

    if ( ++ ( cinfo->output_iMCU_row ) < cinfo->total_iMCU_rows ) {
        return JPEG_ROW_COMPLETED;
    }
    return JPEG_SCAN_COMPLETED;
}

#endif /* D_MULTISCAN_FILES_SUPPORTED */


#ifdef BLOCK_SMOOTHING_SUPPORTED

/*
 * This code applies interblock smoothing as described by section K.8
 * of the JPEG standard: the first 5 AC coefficients are estimated from
 * the DC values of a DCT block and its 8 neighboring blocks.
 * We apply smoothing only for progressive JPEG decoding, and only if
 * the coefficients it can estimate are not yet known to full precision.
 */

/*
 * Determine whether block smoothing is applicable and safe.
 * We also latch the current states of the coef_bits[] entries for the
 * AC coefficients; otherwise, if the input side of the decompressor
 * advances into a new scan, we might think the coefficients are known
 * more accurately than they really are.
 */

LOCAL boolean
smoothing_ok( j_decompress_ptr cinfo ) {
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
    boolean smoothing_useful = FALSE;
    int ci, coefi;
    jpeg_component_info * compptr;
    JQUANT_TBL * qtable;
    int * coef_bits;
    int * coef_bits_latch;

    if ( ( !cinfo->progressive_mode ) || ( cinfo->coef_bits == NULL ) ) {
        return FALSE;
    }

    /* Allocate latch area if not already done */
    if ( coef->coef_bits_latch == NULL ) {
        coef->coef_bits_latch = (int *)
                                ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
                                                             cinfo->num_components *
                                                             ( SAVED_COEFS * SIZEOF( int ) ) );
    }
    coef_bits_latch = coef->coef_bits_latch;

    for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
          ci++, compptr++ ) {
        /* All components' quantization values must already be latched. */
        if ( ( qtable = compptr->quant_table ) == NULL ) {
            return FALSE;
        }
        /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
        for ( coefi = 0; coefi <= 5; coefi++ ) {
            if ( qtable->quantval[coefi] == 0 ) {
                return FALSE;
            }
        }
        /* DC values must be at least partly known for all components. */
        coef_bits = cinfo->coef_bits[ci];
        if ( coef_bits[0] < 0 ) {
            return FALSE;
        }
        /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
        for ( coefi = 1; coefi <= 5; coefi++ ) {
            coef_bits_latch[coefi] = coef_bits[coefi];
            if ( coef_bits[coefi] != 0 ) {
                smoothing_useful = TRUE;
            }
        }
        coef_bits_latch += SAVED_COEFS;
    }

    return smoothing_useful;
}


/*
 * Variant of decompress_data for use when doing block smoothing.
 */

METHODDEF int
decompress_smooth_data( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) {
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
    JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
    JDIMENSION block_num, last_block_column;
    int ci, block_row, block_rows, access_rows;
    JBLOCKARRAY buffer;
    JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
    JSAMPARRAY output_ptr;
    JDIMENSION output_col;
    jpeg_component_info * compptr;
    inverse_DCT_method_ptr inverse_DCT;
    boolean first_row, last_row;
    JBLOCK workspace;
    int * coef_bits;
    JQUANT_TBL * quanttbl;
    INT32 Q00, Q01, Q02, Q10, Q11, Q20, num;
    int DC1, DC2, DC3, DC4, DC5, DC6, DC7, DC8, DC9;
    int Al, pred;

    /* Force some input to be done if we are getting ahead of the input. */
    while ( cinfo->input_scan_number <= cinfo->output_scan_number &&
            !cinfo->inputctl->eoi_reached ) {
        if ( cinfo->input_scan_number == cinfo->output_scan_number ) {
            /* If input is working on current scan, we ordinarily want it to
             * have completed the current row.  But if input scan is DC,
             * we want it to keep one row ahead so that next block row's DC
             * values are up to date.
             */
            JDIMENSION delta = ( cinfo->Ss == 0 ) ? 1 : 0;
            if ( cinfo->input_iMCU_row > cinfo->output_iMCU_row + delta ) {
                break;
            }
        }
        if ( ( *cinfo->inputctl->consume_input )( cinfo ) == JPEG_SUSPENDED ) {
            return JPEG_SUSPENDED;
        }
    }

    /* OK, output from the virtual arrays. */
    for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
          ci++, compptr++ ) {
        /* Don't bother to IDCT an uninteresting component. */
        if ( !compptr->component_needed ) {
            continue;
        }
        /* Count non-dummy DCT block rows in this iMCU row. */
        if ( cinfo->output_iMCU_row < last_iMCU_row ) {
            block_rows = compptr->v_samp_factor;
            access_rows = block_rows * 2;/* this and next iMCU row */
            last_row = FALSE;
        } else {
            /* NB: can't use last_row_height here; it is input-side-dependent! */
            block_rows = (int) ( compptr->height_in_blocks % compptr->v_samp_factor );
            if ( block_rows == 0 ) {
                block_rows = compptr->v_samp_factor;
            }
            access_rows = block_rows;/* this iMCU row only */
            last_row = TRUE;
        }
        /* Align the virtual buffer for this component. */
        if ( cinfo->output_iMCU_row > 0 ) {
            access_rows += compptr->v_samp_factor;/* prior iMCU row too */
            buffer = ( *cinfo->mem->access_virt_barray )
                     ( (j_common_ptr) cinfo, coef->whole_image[ci],
                      ( cinfo->output_iMCU_row - 1 ) * compptr->v_samp_factor,
                      (JDIMENSION) access_rows, FALSE );
            buffer += compptr->v_samp_factor;/* point to current iMCU row */
            first_row = FALSE;
        } else {
            buffer = ( *cinfo->mem->access_virt_barray )
                     ( (j_common_ptr) cinfo, coef->whole_image[ci],
                      (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE );
            first_row = TRUE;
        }
        /* Fetch component-dependent info */
        coef_bits = coef->coef_bits_latch + ( ci * SAVED_COEFS );
        quanttbl = compptr->quant_table;
        Q00 = quanttbl->quantval[0];
        Q01 = quanttbl->quantval[1];
        Q10 = quanttbl->quantval[2];
        Q20 = quanttbl->quantval[3];
        Q11 = quanttbl->quantval[4];
        Q02 = quanttbl->quantval[5];
        inverse_DCT = cinfo->idct->inverse_DCT[ci];
        output_ptr = output_buf[ci];
        /* Loop over all DCT blocks to be processed. */
        for ( block_row = 0; block_row < block_rows; block_row++ ) {
            buffer_ptr = buffer[block_row];
            if ( ( first_row ) && ( block_row == 0 ) ) {
                prev_block_row = buffer_ptr;
            } else {
                prev_block_row = buffer[block_row - 1];
            }
            if ( ( last_row ) && ( block_row == block_rows - 1 ) ) {
                next_block_row = buffer_ptr;
            } else {
                next_block_row = buffer[block_row + 1];
            }
            /* We fetch the surrounding DC values using a sliding-register approach.
             * Initialize all nine here so as to do the right thing on narrow pics.
             */
            DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
            DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
            DC7 = DC8 = DC9 = (int) next_block_row[0][0];
            output_col = 0;
            last_block_column = compptr->width_in_blocks - 1;
            for ( block_num = 0; block_num <= last_block_column; block_num++ ) {
                /* Fetch current DCT block into workspace so we can modify it. */
                jcopy_block_row( buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1 );
                /* Update DC values */
                if ( block_num < last_block_column ) {
                    DC3 = (int) prev_block_row[1][0];
                    DC6 = (int) buffer_ptr[1][0];
                    DC9 = (int) next_block_row[1][0];
                }
                /* Compute coefficient estimates per K.8.
                 * An estimate is applied only if coefficient is still zero,
                 * and is not known to be fully accurate.
                 */
                /* AC01 */
                if ( ( ( Al = coef_bits[1] ) != 0 ) && ( workspace[1] == 0 ) ) {
                    num = 36 * Q00 * ( DC4 - DC6 );
                    if ( num >= 0 ) {
                        pred = (int) ( ( ( Q01 << 7 ) + num ) / ( Q01 << 8 ) );
                        if ( ( Al > 0 ) && ( pred >= ( 1 << Al ) ) ) {
                            pred = ( 1 << Al ) - 1;
                        }
                    } else {
                        pred = (int) ( ( ( Q01 << 7 ) - num ) / ( Q01 << 8 ) );
                        if ( ( Al > 0 ) && ( pred >= ( 1 << Al ) ) ) {
                            pred = ( 1 << Al ) - 1;
                        }
                        pred = -pred;
                    }
                    workspace[1] = (JCOEF) pred;
                }
                /* AC10 */
                if ( ( ( Al = coef_bits[2] ) != 0 ) && ( workspace[8] == 0 ) ) {
                    num = 36 * Q00 * ( DC2 - DC8 );
                    if ( num >= 0 ) {
                        pred = (int) ( ( ( Q10 << 7 ) + num ) / ( Q10 << 8 ) );
                        if ( ( Al > 0 ) && ( pred >= ( 1 << Al ) ) ) {
                            pred = ( 1 << Al ) - 1;
                        }
                    } else {
                        pred = (int) ( ( ( Q10 << 7 ) - num ) / ( Q10 << 8 ) );
                        if ( ( Al > 0 ) && ( pred >= ( 1 << Al ) ) ) {
                            pred = ( 1 << Al ) - 1;
                        }
                        pred = -pred;
                    }
                    workspace[8] = (JCOEF) pred;
                }
                /* AC20 */
                if ( ( ( Al = coef_bits[3] ) != 0 ) && ( workspace[16] == 0 ) ) {
                    num = 9 * Q00 * ( DC2 + DC8 - 2 * DC5 );
                    if ( num >= 0 ) {
                        pred = (int) ( ( ( Q20 << 7 ) + num ) / ( Q20 << 8 ) );
                        if ( ( Al > 0 ) && ( pred >= ( 1 << Al ) ) ) {
                            pred = ( 1 << Al ) - 1;
                        }
                    } else {
                        pred = (int) ( ( ( Q20 << 7 ) - num ) / ( Q20 << 8 ) );
                        if ( ( Al > 0 ) && ( pred >= ( 1 << Al ) ) ) {
                            pred = ( 1 << Al ) - 1;
                        }
                        pred = -pred;
                    }
                    workspace[16] = (JCOEF) pred;
                }
                /* AC11 */
                if ( ( ( Al = coef_bits[4] ) != 0 ) && ( workspace[9] == 0 ) ) {
                    num = 5 * Q00 * ( DC1 - DC3 - DC7 + DC9 );
                    if ( num >= 0 ) {
                        pred = (int) ( ( ( Q11 << 7 ) + num ) / ( Q11 << 8 ) );
                        if ( ( Al > 0 ) && ( pred >= ( 1 << Al ) ) ) {
                            pred = ( 1 << Al ) - 1;
                        }
                    } else {
                        pred = (int) ( ( ( Q11 << 7 ) - num ) / ( Q11 << 8 ) );
                        if ( ( Al > 0 ) && ( pred >= ( 1 << Al ) ) ) {
                            pred = ( 1 << Al ) - 1;
                        }
                        pred = -pred;
                    }
                    workspace[9] = (JCOEF) pred;
                }
                /* AC02 */
                if ( ( ( Al = coef_bits[5] ) != 0 ) && ( workspace[2] == 0 ) ) {
                    num = 9 * Q00 * ( DC4 + DC6 - 2 * DC5 );
                    if ( num >= 0 ) {
                        pred = (int) ( ( ( Q02 << 7 ) + num ) / ( Q02 << 8 ) );
                        if ( ( Al > 0 ) && ( pred >= ( 1 << Al ) ) ) {
                            pred = ( 1 << Al ) - 1;
                        }
                    } else {
                        pred = (int) ( ( ( Q02 << 7 ) - num ) / ( Q02 << 8 ) );
                        if ( ( Al > 0 ) && ( pred >= ( 1 << Al ) ) ) {
                            pred = ( 1 << Al ) - 1;
                        }
                        pred = -pred;
                    }
                    workspace[2] = (JCOEF) pred;
                }
                /* OK, do the IDCT */
                ( *inverse_DCT )( cinfo, compptr, (JCOEFPTR) workspace,
                                  output_ptr, output_col );
                /* Advance for next column */
                DC1 = DC2;
                DC2 = DC3;
                DC4 = DC5;
                DC5 = DC6;
                DC7 = DC8;
                DC8 = DC9;
                buffer_ptr++, prev_block_row++, next_block_row++;
                output_col += compptr->DCT_scaled_size;
            }
            output_ptr += compptr->DCT_scaled_size;
        }
    }

    if ( ++ ( cinfo->output_iMCU_row ) < cinfo->total_iMCU_rows ) {
        return JPEG_ROW_COMPLETED;
    }
    return JPEG_SCAN_COMPLETED;
}

#endif /* BLOCK_SMOOTHING_SUPPORTED */


/*
 * Initialize coefficient buffer controller.
 */

GLOBAL void
jinit_d_coef_controller( j_decompress_ptr cinfo, boolean need_full_buffer ) {
    my_coef_ptr coef;

    coef = (my_coef_ptr)
           ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
                                        SIZEOF( my_coef_controller ) );
    cinfo->coef = (struct jpeg_d_coef_controller *) coef;
    coef->pub.start_input_pass = start_input_pass;
    coef->pub.start_output_pass = start_output_pass;
#ifdef BLOCK_SMOOTHING_SUPPORTED
    coef->coef_bits_latch = NULL;
#endif

    /* Create the coefficient buffer. */
    if ( need_full_buffer ) {
#ifdef D_MULTISCAN_FILES_SUPPORTED
        /* Allocate a full-image virtual array for each component, */
        /* padded to a multiple of samp_factor DCT blocks in each direction. */
        /* Note we ask for a pre-zeroed array. */
        int ci, access_rows;
        jpeg_component_info * compptr;

        for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
              ci++, compptr++ ) {
            access_rows = compptr->v_samp_factor;
#ifdef BLOCK_SMOOTHING_SUPPORTED
            /* If block smoothing could be used, need a bigger window */
            if ( cinfo->progressive_mode ) {
                access_rows *= 3;
            }
#endif
            coef->whole_image[ci] = ( *cinfo->mem->request_virt_barray )
                                    ( (j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
                                     (JDIMENSION) jround_up( (long) compptr->width_in_blocks,
                                                            (long) compptr->h_samp_factor ),
                                     (JDIMENSION) jround_up( (long) compptr->height_in_blocks,
                                                            (long) compptr->v_samp_factor ),
                                     (JDIMENSION) access_rows );
        }
        coef->pub.consume_data = consume_data;
        coef->pub.decompress_data = decompress_data;
        coef->pub.coef_arrays = coef->whole_image;/* link to virtual arrays */
#else
        ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif
    } else {
        /* We only need a single-MCU buffer. */
        JBLOCKROW buffer;
        int i;

        buffer = (JBLOCKROW)
                 ( *cinfo->mem->alloc_large )( (j_common_ptr) cinfo, JPOOL_IMAGE,
                                              D_MAX_BLOCKS_IN_MCU * SIZEOF( JBLOCK ) );
        for ( i = 0; i < D_MAX_BLOCKS_IN_MCU; i++ ) {
            coef->MCU_buffer[i] = buffer + i;
        }
        coef->pub.consume_data = dummy_consume_data;
        coef->pub.decompress_data = decompress_onepass;
        coef->pub.coef_arrays = NULL;/* flag for no virtual arrays */
    }
}
